1. Field of the Invention
The present invention relates to a bidirectional clutch for a curtain drawing mechanism which uses a motor.
2. Statement of the Prior Art
Heretofore, curtains have been automatically drawn or opened or pulled up or down by forward or backward movement of a drawing string in engagement with the curtains and driven by a motor through a drive pulley.
In such a device, if automatic driving of the drawing string becomes impossible due to a motor failure or the like, it is then required to manually move the string. However, if a pulley is directly fixed to the drive shaft of the motor, it is impossible to move the string by a moderate force due to the resistance of the motor. For that reason, it is necessary to interpose a clutch mechanism between the pulley around which the drawing string is wound and the motor for rotating the pulley. An electromagnetic clutch has generally been used for this purpose.
A problem with the use of such an electromagnetic clutch is, however, that it is necessary to use an electrical control mechanism for operating it, which makes the associated control structure and system complicated as well as expensive to manufacture.